1. Field of the Invention
The present invention pertains to a method and apparatus for monitoring and controlling a medical device, and, in particular, to a medical device, such as a pressure support system, in which a removeable information storage device selectively inserts into a slot provided in the medical device for monitoring the use or operation of the device, controlling the operation of the device, or both.
2. Description of the Related Art
Pressure support systems that provide a flow of gas to an airway of a patient at an elevated pressure via a patient circuit to treat a medical disorder are well known. For example, it is known to use a continuous positive airway pressure (CPAP) device to supply a flow of breathing gas at a constant positive pressure to the airway of a patient throughout the patient's breathing cycle. This is done to treat obstructive sleep apnea (OSA), for example. The positive pressure provided by the flow of breathing gas effecting splints the airway, thereby preventing its collapse. Examples of CPAP devices are the REMstar® and Solo® family of pressure support devices manufactured and distributed by Respironics, Inc. of Pittsburgh, PA.
In a typical CPAP device, the operating parameters, such as output pressure, and, hence, the flow of fluid delivered to a patient, is set to a predetermined level prescribed by a qualified caregiver. This level is typically clinically determined for each patient, so that the patient receives pressure support at that an appropriate prescribed level. Most conventional pressure support devices allow the pressure level to be changed by an authorized caregiver or technician, so that a commonly designed CPAP device can be used to provide a pressure support therapy to patients requiring different pressure prescription levels. This also allows the patient's prescription pressure to be changed as the needs of that patient change, without having to replace the patient's existing CPAP device with a new CPAP device. Of course, modifying the prescription level should only to be done under a caregiver's supervision. For this reason, access to the ability to change the prescription pressure levels must be tightly controlled to prevent unauthorized tampering or inadvertent modification of the operating parameters of the CPAP device.
It is also known to provide a positive pressure therapy in which the pressure of the breathing gas delivered to the patient varies with the patient's breathing cycle. A conventional ventilator, such as the Esprit® Ventilator, also manufactured by Respironics, is an example of a pressure support or ventilator system in which the pressure of gas delivered to the patient varies between inspiration and expiration so as to replace or supplement the patient's own ventilation. For purposes of the present invention, the phase “pressure support system” includes any medical device, invasive or non-invasive, that delivers a flow of breathing gas to the airway of a patient, including a ventilator.
It is also known to vary the pressure delivered to the patient between inspiration and expiration to increase the comfort for the spontaneously patient, while providing the desired pressure support therapy. For example, it is known to vary the pressure of the breathing gas delivered to the patient in synchronization with the patient's breathing cycle, so that a lower pressure is delivered to the patient during the expiratory phase of the breathing cycle than is delivered during the inspiratory phase. As a result, the patient receives the necessary pressure support during inspiration to treat their disorder, such as OSA, but is not breathing out against a relatively high pressure during expiration, which can be uncomfortable to some patients. This mode of pressure support is typically referred to as “bi-level” pressure support.
With bi-level pressure support therapy, the patient's inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP) are each set to predetermined prescription levels so that the bi-level pressure support device provides the prescribed IPAP and EPAP pressures at the appropriate phase of the breathing cycle. Bi-level pressure support as taught, for example, in U.S. Pat. No. 5,148,802 to Sanders et al., U.S. Pat. No. 5,313,937 to Zdrojkowski et al., U.S. Pat. No. 5,433,193 to Sanders et al., U.S. Pat. No. 5,632,269 to Zdrojkowski et al., U.S. Pat. No. 5,803,065 to Zdrojkowski et al., and U.S. Pat. No. 6,029,664 to Zdrojkowski et al., the contents of each of which are incorporated by reference into the present invention. It is further known to provide a positive pressure therapy mode in which the pressure provided to the patient changes based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, upper airway resistance, or a combination thereof. This mode of pressure support is typically referred to as an “auto-titration” mode of pressure support, because the pressure support device itself determines the optimum pressure to deliver to the patient. With this type of pressure support system, the operating parameters of the system, such as the maximum and minimum pressures that can be output by the device, are typically set in advance and can only be adjusted by an authorized caregiver or technician.
An example of an auto-titration pressure support device that adjusts the pressure delivered to the patient based on whether or not the patient is snoring is the Virtuoso® CPAP family of devices manufactured and distributed by Respironics, Inc. This auto-titration pressure support mode is taught in U.S. Pat. Nos. 5,203,343; 5,458,137 and 6,087,747 all to Axe et al., the contents of which are incorporated herein by reference. An example of a pressure support device that actively tests the patient's airway to determine whether obstruction, complete or partial, could occur and adjusts the pressure output to avoid this result is the Tranquility® Auto CPAP device, also manufactured and distributed by Respironics, Inc. This auto-titration pressure support mode is taught in U.S. Pat. No. 5,645,053 to Remmers et al., the content of which is incorporated herein by reference.
Other modes of providing positive pressure to the patient are also known. For example, a proportional assist ventilation (PAV®) mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort to the patient. U.S. Pat. Nos. 5,044,362 and 5,107,830 both to Younes, the contents of which are incorporated herein by reference, teach a pressure support device capable of operating in a PAV mode. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient. U.S. Pat. Nos. 5,535,738; 5,794,615; and 6,105,573 all to Estes et al., the contents of which are incorporated herein by reference, teach a pressure support device capable of operating in a PPAP mode.
Typically, the appropriate mode of pressure support, e.g., CPAP, bi-level, auto-titration, PPAP, PAV, or a combination thereof is determined by the caregiver based on the results of a sleep study or other criteria, such as the patient's ability to tolerate certain types of pressure support or the objectives of the pressure support therapy. The operating parameters of the pressure support device, such as CPAP level, IPAP and EPAP levels in the case of a bi-level pressure support, percent of assistance in the case of a PAV or PPAP device, maximum/minimum pressure in the case of an auto-titration device, are also prescribed, for example, based on the results of sleep study, the conditions of the patient, and/or the goals to be achieved by the pressure support therapy.
Once the appropriate mode of pressure support is established and the appropriate pressure level or levels or percent of assistance are prescribed, the patient receives a pressure support system that is capable of administering the prescribed pressure support mode within the range of prescribed operating parameters. Prior to beginning the pressure support treatment, the pressure support device provider or other caregiver sets the operating parameters of the pressure support device, such as the prescribed pressure level or levels or percent assistance, based on the prescription for that patient.
Other operating parameters that are typically set by the device provider or other caregiver include enabling or disabling additional features of the pressure support device, such as alarms, the ability to provide a time backup breath, and a pressure ramp, which is a feature in which the pressure level provided to the patient is gradually increased over time to allow the patient to fall asleep under a relatively low pressure. The device provider also typically sets the duration of the ramp period as an operating parameter. As with the operating parameters associated with the prescription pressure discussed above, activating, deactivating or altering other features of the pressure support system is preferably and, in many cases, necessarily done by an authorized caregiver or technician under the direction and/or supervision of the physician or other caregiver responsible for that patient.
For purposes of the present invention, “operating mode” refers to the type of pressure support treatment provided to the patient by the pressure support device, e.g., CPAP, bi-level, auto-titration, PPAP, PAV, or a combination thereof. While a great number of pressure support systems can only operate in one mode, some conventional pressure support systems can operate in different pressure support modes depending on how the system is set up. For example, a typical bi-level pressure support system will operate as a CPAP device if the IPAP and EPAP levels are the same. Typically, once a patient is prescribed a mode of pressure support treatment, to minimize cost, he or she will receive a pressure support device that is only capable of operating in that pressure support mode.
Those skilled in the art can also appreciate that a conventional ventilator system is typically capable of operating in different ventilation modes, with each mode representing a different technique for triggering and/or cycling the ventilator. It is common in a ventilator, for the caregiver to be able to select from a variety of modes of ventilation using selection devices provided on the ventilator. Because a ventilator is typically used in a hospital or other highly supervised environment, there is less chance that the patient or others will intentionally or inadvertently alter the operating mode of the system.
The phase “operating parameter” used herein refers to all other variables that can be altered or controlled in each operating mode. For example, in a CPAP device, the CPAP level is considered an operating parameter. In a bi-level device, the IPAP and EPAP levels are operating parameters. In the case of a PAV or PPAP device, the operating parameter is the percent of assistance provided by the device. In an auto-titrating device, the maximum/minimum pressures, amount of pressure change during each pressure increment or decrement, and breathing disorder event detection thresholds are examples, of operating parameters. It is to be understood that this list is not exclusive. Those skilled in the art can appreciate that other features of the pressure support or ventilation system can be controlled by the user, technician, caregiver or others. In general, an operating parameter includes any feature of the system that can be manually controlled directly or indirectly, such as whether to activate the pressure ramp discussed above and the duration of the ramp.
Physically setting the operating mode and/or parameters, including enabling and disabling features of the pressure support device, typically is done by manually setting a switch, dial, knob or other input device on the pressure support device. Depending on the capabilities of the pressure support device, it is also accomplished by downloading the operating mode and/or operating parameters directly into a controller in the pressure support device via a dedicated RS232 port. This assumes, or course, that the pressure support system allows for modification of the operating mode or parameters and can support the selected mode and parameter.
Either of these techniques for setting up the pressure support system require the device provider, technician, or other authorized person to physically open the pressure support device to gain access to the input setting components that are otherwise inaccessible to the patient, to have access to the input devices on the system for changing the mode or parameters using an authentication/authorization protocol, have access to the computer terminal on the device, or any combination thereof. As noted above, the pressure support device is configured such that setting or changing the operating mode and/or operating parameters can only be accomplished by an authorized technician or caregiver. This prevents the patient or others from intentionally or accidentally changing the operating mode and/or parameters, such as the prescription pressure level(s) once they are set by the caregiver. That is, once the operating parameters of the pressure device have been set, the patient begins using the device to treat their breathing disorder and the operating mode and/or parameters remain in effect as long as the patient uses the device. Only a person having the proper knowledge, equipment, training, access codes, etc. can gain access to the ability to alter the operating mode or parameters of the medical device.
It can be appreciated that it may be necessary for the patient to be switched to a different operating mode, different operating parameters, or both over the course of their diagnosis and/or treatment. It can be further appreciated that the operating mode or parameters should only be changed under the supervision of an authorized caregiver. As a result, changing the set up of the pressure support system is a burdensome process requiring an excessive amount of effort from the caregiver, device provider, or other authorized person responsible for servicing the prescribed pressure support system.
For example, it is not uncommon for an OSA sufferer to initially be treated with a CPAP device, and, thereafter, switched to a bi-level device in order to increase their comfort and compliance with the pressure support therapy. Using conventional pressure support systems, this switch requires that the patient receive an entirely new bi-level device in place of the CPAP device. This is obviously expensive and burdensome on the healthcare provider, who must deliver and install the new bi-level system in place of the existing CPAP device. Alternatively, a bi-level device could be prescribed to the patient with the IPAP and EPAP levels set to the same pressure for the CPAP treatment, then changed to different levels for the bi-level treatment. However, this approach is also not practical because, as noted below, changing even the IPAP and/or EPAP prescription levels requires that the authorized person have access to the device, for example, by visiting the patient's home, to make the prescription pressure change.
It is also not uncommon for the need to arise to change the operating parameters of the system. For example, there is often a need to change the prescription pressure output by the pressure support device, the duration of the pressure ramp, or the features of the system, over the course of the patient's support therapy. It can be appreciated from the above-description of how these parameters are set, that changing the operating parameters is a relatively complicated and cumbersome process and cannot be done by the patient. For example, if the patient's initial CPAP or IPAP prescription pressure is too low, increasing the prescription pressure requires that the pressure support device provider or other authorized caregiver visit the patient's home where the unit is located to make the necessary modifications. Of course, the patient can return the pressure support device to the provider to make the changes at their facility. Either scenario imposes a significant burden on the patient, the device provider, or both.
Because each conventional pressure support system is tailored to the needs of one patient and cannot be changed except under the supervision of a caregiver, each patient is, in effect, only able to use the pressure support device that has been tailored to his or her medical needs. That is, each patient has a unique pressures support therapy prescription determined by a caregiver, and the patient receives a pressure support system configured to conform to that prescription. Therefore, in order to receive the prescribed pressure support treatment, the patient must have his or her specifically configured device with them, and not some other pressure support device, because the other pressure support device cannot be readily altered to conform to that patient's prescription. It can be appreciated that this represents a significant burden on the patient, especially if patient travels frequently. In which case, the patient subjects the pressure support device to damage and wear during transportation or must have multiple pressure support systems available, one for home and one for travel.
Of growing importance with respect to pressure support systems is the ability to monitor the patient's use of the prescribed pressure support device, typically referred to as their “compliance” with the prescribed therapy. For example, a cost conscious healthcare provider may require that the compliance data be recorded and monitored before a reimbursement is made. Numerous techniques exist for monitoring and measuring the patient's compliance with the prescribed pressure therapy. However, a difficulty exists in reliably and accurately reporting the compliance data to a caregiver or healthcare provider.
Most conventional pressure support systems generate compliance data and store it in memory for downloading to an external computer via an RS232 port and/or for display on a display screen in the pressure support device. Other conventional pressure support devices increment a compliance meter visible on the unit. These compliance monitoring techniques require that the device provider or other caregiver physically inspect the pressure support device or physically access the device in order to view or download the compliance data.
It is also known to download compliance data from a pressure support device to a central location via a modem. This technique, however, requires that the patient have access to an available telephone jack and be trained in how to configure the system to use the telephone modem. It also requires that the pressure support system include dedicated circuitry, such as an internal modem or a modem jack, so that the modem can be installed on the device for communicating via conventional communication techniques with a central receiving station. It can be appreciated that providing such dedicated components increases the cost and complexity of the pressure support device. Therefore, it is preferable not to include dedicated communication circuitry in every pressure support system, especially if only a small percentage of patients need to monitored this closely. In addition, the data receiving center that accumulates the compliance data via a modem must have the ability to receive, identify and organize the incoming data, which requires a relatively complicated, automated data processing capability.